How can the savannah elephant afford to produce feces richer than its food? part 4

In which ways can the digestive system of Loxodonta africana be seen as efficient?

A short answer is: in the meeting of requirements for certain micronutrients crucial for the particular physiological needs of this species with its exceptional cerebellum.

Please consider that:

  • although the digestibility of most components of food is small, that of certain crucial micronutrients is likely to be great, and
  • if L. africana ate any less than it does, it would not be able to get enough of these nutrients regardless of how thorough its digestion and absorption might be.

An aspect of partial digestion is that certain food-components will, by virtue of their chemical properties, be extracted more thoroughly than others. Certain nutrients are easily absorbed, such as potassium (which is extremely soluble) and iodine (which is extremely volatile). Others are hard to absorb (particularly metals such as zinc and iron).

By the same token, the vagaries of composition mean that a given diet can be sufficient in almost all nutrients yet deficient in a few chemically peculiar nutrients. In particular, iodine (https://en.wikipedia.org/wiki/Iodine#Deficiency) and selenium (https://en.wikipedia.org/wiki/Selenium#Deficiency) happen not to be essential for plants in the ways they are for animals (https://www.researchgate.net/publication/229774801_Why_are_very_large_herbivores_absent_from_Australia_A_new_theory_of_micronutrients and http://vro.agriculture.vic.gov.au/dpi/vro/vrosite.nsf/pages/trace_elements_pastures_pdf2/$FILE/trace%20elements%20ch7.pdf). Therefore plant matter tends to be poor in these micronutrients.

This problem is exacerbated at extreme body size because the larger the mouthparts the harder it is to select those plant tissues relatively rich in these micronutrients.

Furthermore, iodine and selenium are particularly important for the development of the brain (https://pubmed.ncbi.nlm.nih.gov/25880137/#:~:text=Iodine%20is%20an%20essential%20micronutrient,mental%20impairment%20in%20the%20world.).

Loxodonta africana has, relative to body size, an extremely large brain for a terrestrial, non-primate herbivore. In particular, the cerebellum is exceptionally well-developed (https://www.researchgate.net/figure/The-human-brain-is-not-the-largest-Brains-of-a-human-and-of-an-African-elephant-are_fig7_38091649 and https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4053853/).

Several lines of evidence suggest that, for L. africana, iodine may be a crucial nutrient (see pages 6-7 in https://peerj.com/articles/6260.pdf).

The above ideas may help to explain how the digestive system of L. africana may be efficient in the context of the extreme body size and exceptional braininess of this species among land mammals other than primates.

To summarise, I suggest that L. africana capitalises on quantity of available plant matter, promotes regeneration quasi-horticulturally, and efficiently 'skims' those nutrients - particularly iodine and selenium - that are easily absorbed and crucial for its physiological peculiarities. These functions result in wastage of most food-components and minimal incentive to eat feces. The overall result is feces so rich that they are an important source of food for other animals.

Posted on Ιανουάριος 31, 2022 0840 ΠΜ by milewski milewski

Σχόλια

Αναρτήθηκε από milewski σχεδόν 2 χρόνια πριν
Αναρτήθηκε από milewski σχεδόν 2 χρόνια πριν
Αναρτήθηκε από milewski σχεδόν 2 χρόνια πριν
Αναρτήθηκε από milewski σχεδόν 2 χρόνια πριν
Αναρτήθηκε από milewski σχεδόν 2 χρόνια πριν
Αναρτήθηκε από milewski σχεδόν 2 χρόνια πριν

Προσθήκη σχόλιου

Συνδεθείτε ή Εγγραφή για να προσθέσετε σχόλια